1. Field of the Invention
The present invention relates to a hybrid power system with continuously variable speed, particularly to a hybrid power system with continuously variable speed to be used in conjunction with a small internal combustion engine and an electric motor.
2. Description of Related Art
A conventional vehicle is driven by an internal combustion engine. An internal combustion engine generates power that is transmitted to wheels to drive the vehicle. Since internal combustion engines operate by burning fuel, exhaust gas is produced, polluting air. For protecting the environment, electrically driven vehicles have been developed, having no internal combustion engines, but being driven by electric motors powered by batteries. In an electrically driven vehicle, electric energy stored in a battery is converted to mechanical energy by a motor. Mechanical power is by a gear transmitted to wheels. However, batteries have limited energy storage capabilities, so mileage of electrically driven vehicles is insufficient and generally do not meet motorists"" demands. Electrically driven vehicles have therefore been sold only in small quantities and are not widely used. For this reason, vehicles driven by hybrid power systems have been developed, each having an engine and an electric motor. By suitable arranging of a transmission device, varying output of power is generated, with torque of the engine and the electric motor adapted appropriately to each other. Thus effective operation is achieved under various conditions, such as climbing, descending, braking and accelerating. An ideal combination of both motors results in efficient operation with high power output and low exhaust gas generation.
Due to a wide variety of transmission devices, hybrid power systems with varying components and varying effects exist. Currently, hybrid power systems are mostly used in four-wheel cars, with hundreds of systems having been developed and large competition between major car manufacturers.
However, small vehicles which are driven by small engines, like light motorcycles and minicars, have little space and need to be inexpensive. So it is difficult to install transmission devices for hybrid power systems of small vehicles. Consequently, very few hybrid power systems are used in small vehicles. Although some research is being done and several related inventions have been made, there is only a narrow range of applications of hybrid power systems small vehicles.
In conventional art, several patents concerning hybrid power systems have been disclosed. Therein, an epicyclic train is taught, where a sun gear and planet gear is driven by an engine and an electric motor. Power output is at a ring gear. Since no torque converter is installed between the engine and the epicyclic train, any change of speed leads to jerks, with the engine and the electric motor not being adapted to each other. When the engine slows down, there is no way to interrupt power transmission. Thus this power transmission device is impractical.
Therefore, a hybrid power system for small vehicles is not only required to be accommodated in a small space, but also to allow for independent operation of the engine and the electric motor, as well as for smooth adaptation thereof to each other. Furthermore, it is desirable to regenerate electric energy by operating the engine and taking advantage of momentum of the moving vehicle. Then a comprehensive effect of the hybrid power system is achieved. At the same time, a direction of development of small power devices, as for motorcycles and minicars, is marked.
It is the object of the present invention to provide a hybrid power system with continuously variable speed which is inexpensive.
In the present invention, an engine and an electric motor are connected, delivering output on a single shaft, so that various modes of delivering power and driving are feasible. The engine and the electric motor are connected by a speed converter having a V-shaped belt for smooth mutual connection and controlled by controlling devices, so that the following functions are effectively performed:
1. the engine running slowly or stopped, with the electric motor running idle;
2. the engine running slowly or stopped, with the electric motor driving the vehicle forward;
3. the engine running slowly or stopped, with the electric motor driving the vehicle rearward;
4. the engine running, via the speed converter with V-shaped belt driving the vehicle, with the electric motor running idle;
5. the engine running, via the speed converter with V-shaped belt driving the vehicle, with the electric motor generating electricity;
6. the engine running, via the speed converter driving the vehicle, with the electric motor in addition driving the vehicle;
7. the engine slowing down or stopping, with the electric motor generating electricity due to momentum of the vehicle slowing down;
8. the engine running, with the electric motor running idle and an electric generator attached to the engine generating electricity, while the vehicle rests.
The present invention employs a standard engine and a standard electric motor, which are readily available on the market, so cost is saved. By having a second transmission device, an even wider range of engines and electric motors is usable, allowing for flexible adapting to various power standards and a wide range of operating conditions. At the same time, restriction of space is easily accommodated. The present invention is usable in conjunction with two-wheel as well as four-wheel vehicles, ensuring a wide range of applications.
The present invention can be more fully understood by reference to the following description and accompanying drawings.